title: Cytogenetic signature for ionizing radiation.
abstract: A stable, easily measurable biological 'signature' for past exposure to densely ionizing radiation would be of significant value to estimate environmental radiation risk. Defined here, the S-ratio is the ratio of complete to incomplete chromosome translocations. It constitutes a clastogenic signature that appears to be stable over time, independent of dose, and varies inversely with the relative biological effectiveness (RBE) of the radiation. In vitro measurements resulted in a ratio of approximately 2 for densely ionizing radiation (56Fe and 12C ions) in contrast to a value of approximately 10 for sparsely ionizing radiation (X- and gamma-rays). The measured ratio was approximately 2 for bleomycin and benzene. Such a distinctive clastogenic signature should facilitate better estimates of neutron dose for A-bomb survivors, as well as a causal connection between early exposure to densely ionizing radiation and late development of cancer.
authors.affiliation: University of California, Lawrence Livermore National Laboratory, Livermore, CA 94551, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Lucas
mesh_terms: D000818:Animals; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects*; D004249:DNA Damage; D006801:Humans; D018499:Linear Energy Transfer; D008214:Lymphocytes / Q000528:radiation effects